Unix seconds vs milliseconds — how do I tell them apart?

By magnitude. Unix seconds for dates between 2001 and 2286 are 10 digits (1e9 to 1e10); milliseconds are 13 digits (1e12 to 1e13). If the number has 13 digits, it is likely milliseconds. The tool auto-detects, but always verify the converted date is reasonable.

Why does my timestamp convert to a different date in another timezone?

A Unix timestamp is absolute (seconds since 1970-01-01 UTC). The date string representation changes by timezone: 1700000000 is 2023-11-14 22:13:20 UTC but 2023-11-15 07:13:20 in JST. The moment is the same; the display differs.

TASK

Convert between Unix timestamp, ISO 8601, and human-readable dates

Translate a time value between Unix epoch seconds, milliseconds, ISO 8601, and local/UTC date strings.

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Timestamps come in many forms: Unix seconds (1700000000), milliseconds (1700000000000), ISO 8601 (2023-11-14T22:13:20Z), RFC 2822, and locale strings. Converting between them is a frequent need when bridging APIs and databases.
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Timestamp Converter →
Paste a timestamp in any common format. The tool detects the format and outputs all equivalents: Unix s, Unix ms, ISO 8601 UTC, and human-readable in selected timezones.
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Timezone Converter →
Convert the timestamp to a specific timezone for display — essential for scheduling apps that show times in the user's local zone.

Frequently asked questions

Unix seconds vs milliseconds — how do I tell them apart?: By magnitude. Unix seconds for dates between 2001 and 2286 are 10 digits (1e9 to 1e10); milliseconds are 13 digits (1e12 to 1e13). If the number has 13 digits, it is likely milliseconds. The tool auto-detects, but always verify the converted date is reasonable.
Why does my timestamp convert to a different date in another timezone?: A Unix timestamp is absolute (seconds since 1970-01-01 UTC). The date string representation changes by timezone: 1700000000 is 2023-11-14 22:13:20 UTC but 2023-11-15 07:13:20 in JST. The moment is the same; the display differs.